Nucleate boiling heat transfer coefficients may be strongly reduced by scale formation, even for conditions where the bulk foulant concentration is well below the saturation concentration. Due to the mechanism of micro-layer evaporation, the local concentration at the heat transfer surface can be considerably increased, causing the formation of scale and changes in bubble frequency and bubble d...

copper matrix composite reinforced by 1wt.% tib2 particles was prepared using in situ reaction of cu-1.4wt.% ti and cu-0.7wt.% b by rapid solidification and subsequent heat treatment for 1-20 hrs at 900ºc. high-resolution transmission electron microscopy (hrtem) characterization showed that primary tib2 particles were formed in liquid copper. heat treatment of as-solidified samples led to the f...

In this study, time of calcium phosphate formation on Ti6Al4V alloy with or without alkali and heat treatments was investigated. Specimens were soaked in 0, 5, 10 M solutions of NaOH at temperatures of 60 or 80 °C for 24, 72 h. Their surfaces were characterized using scanning electron microscopy and thin film X-ray diffraction. It was found that optimum condition is 72h soaking in 5 M NaOH in 8...

Copper matrix composite reinforced by 1wt.% TiB2 particles was prepared using in situ reaction of Cu-1.4wt.% Ti and Cu-0.7wt.% B by rapid solidification and subsequent heat treatment for 1-20 hrs at 900ºC. High-resolution transmission electron microscopy (HRTEM) characterization showed that primary TiB2 particles were formed in liquid copper. Heat treatment of as-solidified samples led to ...

al2o3-sio2 diphasic gel was synthesized by sol gel route from aluminium nitrate and silicic acid following aqueous phase colloidal interaction. the precursor gel powder was thoroughly characterized by chemical analysis, measurement of surface area and bulk density measurement. the gel powder was further characterized by thermogravimetry, xrd diffraction study of the heat treated samples and sca...

Abstract: Two different coating microstructures of Ni-50Cr alloy were obtained on a stainless steel substrate by changing combustion characteristics of a high velocity oxy-fuel (HVOF) process and the size distribution of feed powder during coating process. Use of the finer feed powder and leaner fuel in oxygen/fuel ratio (i.e. using a ratio much less than stoichiometric ratio) led to formati...

The weldability of GTD-111 nickel-based superalloy by pulsed Nd:YAG laser welding with an average power of 250 W was studied, and the microstructural evolution and cracking characteristics were also investigated. The solidification cracking of the fusion zone (FZ) and the intergranular liquation cracking in the heat affected zone (HAZ) were observed in the joint. Solidification cracking was cau...